Much of the Midwest has experienced mild and humid weather over the past few weeks, which has influenced disease development. Gray leaf spot levels have been at low to moderate levels in most areas, but northern corn leaf blight, which appears as cigar-shaped gray and tan lesions on leafs, has developed rapidly.
Much of the Midwest has experienced mild and humid weather over the past few weeks, which has influenced disease development. Gray leaf spot levels have been at low to moderate levels in most areas, but northern corn leaf blight, which appears as cigar-shaped gray and tan lesions on leafs, has developed rapidly.
BLOOMINGTON, Ill. — Growing conditions are ideal for northern corn leaf blight, and producers are urged to scout their fields.

AJ Woodyard, BASF technical crop protection specialist, said northern corn leaf blight is an aggressive disease when it sets in and has become a larger issue for corn growers.

“Northern corn leaf blight thrives in weather conditions when we’re in the range of 64 to 81 degrees, when we’ve been wet and when we’ve had some humidity,” he said.

“So, in a lot of the corn-growing region, there’s been ideal conditions for northern corn leaf blight to develop because we’ve had wet conditions, the right temperatures, and we’re starting already see this disease set in and become an issue.”

Due to its aggressive nature, Woodyard recommends growers need to be scouting for blight in their fields.

The disease appears as a large gray and tan cigar-shaped lesion on leafs. Lesions may contain prominent, dark areas of sporulation as they mature, and the length or size of lesions may vary with their different reactions to resistant genes within corn hybrids.

“It’s very identifiable when you’re out in the field, and the symptoms will very quickly spread,” Woodyard said.

He said northern corn leaf blight can rob crop yield quickly, which is why he recommends growers proactively manage the disease and not let it spread into the crop canopy.

Fungicide Protection

“As part of that proactive strategy, we want to apply Headline AMP fungicide to protect that crop from diseases,” Woodyard said.

“Headline AMP is the absolute best product with its two outstanding active ingredients that manage northern corn leaf blight very well, and it’s also important to keep in mind that in order to manage it we need to be ahead of that disease.”

He recommends application timing from full tassel to the beginning of the milk stage.

“From VT to R3 is the most important time to be out there taking a look for northern corn leaf blight and making sure we get that proactive application out in that field,” he said.

There are several strategies corn growers can use to prevent effects of northern corn leaf blight, Woodyard said.

One is to rotate corn and soybean crops to reduce the chance of disease development.

For corn on corn, Woodyard suggests a couple of other strategies.

“One would be to try to manage our residue. We want to get as much of that residue buried below ground to not allow that fungal spore to germinate on the surface and splash up on the plant,” he said.

“The other thing would be to manage it with hybrid tolerance. The last thing would be proactive fungicide applications with something like Headline AMP that will allow you to manage that disease before it can ever set in and keep that tissue working for you to feed the grain.”